Abrasive supply system



Dec. 26, 1944.. M, GOSSARD A 2,365,948 l Y ABRAvSIVE SUPPLY SYSTEM Original Filed April 27, 1942 @AM www Patented Dec. 26, 1944 f uNITED'N STATES PATENroFFIcE Charles M. Gossard, Hagerstown, Md., assignorV to Pangborn Corporation, Hagerstown, Md., a

corporation of Maryland I Original application pril 27, 1942, Serial No. 440,689. Divided and this application February 29, 1944, Serial No. 524,495

45 Claims. (Cl. 51e-12) vices or machines for projecting such particles at abrading or blasting Ivelocities and moreparticularly pertains to means for` automatically con- 12. trolling the addition of newv or fresh particles to the abrasive in a system circulating abrasive particles through abrasive. projecting apparatus.

.This application Vis a division of application Serial No. 440,639, med April 27, `1942.

to apparatus for projecting theparticlesusually includes a bin in which a main supply of abrasive is stored. The machine or device for projecting from into a position for beingr acted on4 by the propelling apparatus, The prior arrangements often include means for recovering the spent par-j The present invention relates to apparatus for replenishing the abrasive particles supplied to de- A t Y l0 A conventional system` for supplying abrasive' ticles projected by the machine Vor blast nozzlesV and means for returning the collected particles to the main" bin or. hopper for recirculation through the abrading or blasting'apparatus. The

impingement of the particles on articles to beg cleaned or abraded,y or on the surface of the material to be treated, causes some of the particles to be broken, and further recirculation of the abrasive particles in such substantially closed circuit supply system will cause further particles to `be broken whereby substantial disintegration takes place and new orfresh abrasive must be I j added to the main bin. It has been customary `in the past to add sumcient new or unbroken abrasive particles to the main bin at the beginning-` of a blasting or abrading operation sothat the articles or material blasted or abraded immediately thereafter areengaged by unbroken particles, `but later during' operation the articles or A further object of the invention resides in providing means for automatically controlling the admission of abrasive particles from an auxiliary supply to the systemfeeding abrasive to the projecting apparatus andin such a manner that the new abrasive will bemixed with or 'distributed throughout the used abrasive.

Other. objects and features of the invention will be more apparent to thoseskilled in the art upon a consideration of the accompanying drawing and the following detailed description wherein an exemplary embodiment ofthe invention is disclosed.

The drawing isa diagrammatic View showing an organization of apparatusembodying the invention and illustrating means vfor controlling movement of particles from an auxiliary supply 4to the main abrasive circuit.

particles suitable for4 an .abrading or blasting operation. The abrasive stored in the bin l0 may be of any type such as metal particles, steel shot,

.sand or othersuitable granular material, The

apparatus includes means for guiding the abrasive from the main bin I0 downwardly into apparatus for projecting the abrasive particles. Such guide means may take the form of a feed spout or conduit Il for directing or guiding the abrasive into an operativeposition in relation to the projecting apparatus ,shown generally at I 2. rAny type of machine or device may be employed for projecting the abrasive particles, and for the purposes ofillustrationonly a rotor or wheel is shownvfor, accelerating the abrasive and projecting thel abrasive particles ontoV articles to be cleaned or abraded. The abrasive projecting apparatus may include a rotor as disclosed in the patent to Keefer, No. 2,108,005, having a series of blades for projecting the abrasive particles in any Lmaterial are blasted or abraded with broken orv 40 direction and in one example the abrasive Stream smallerparticle Thus the abrading or S directed downwardly als indicated by the dotted operations Carried `out the prior arrangelines articleshsuch-aas a plurality of ments do not provide a uniform treatment of the Castings '5- y surface of the articles or material being abraded The projected abrasive Particles are Collected or blasted, I l 45 and returned to the main bin I0 by any suitable It is thereforean object of the present invenmeans Which may include a housing I7 haVlg tion to avoidmaterial or detrimentalv variations S10png'side Walls, Worm cnveyor means Shown in the character of theabrasive material by autoat i8 and an elevator type COIlVel/OT means nmatically adding abrasive particles tothe abrasive dicated generally at I9. 'Ihe W01I1'1 COHVSYOI I3 supply circuit and thereby maintain the abrasive 50 may be mounted in ant7 COHVGYIOIlalmal-fllel S0 in the system at a substantially uniform degree as to move the spent abrasive particles into the of brokenness. Thus, different articles or matecasing of the elevator I9. The elevator may also rials blasted or abraded throughout an extended be of a conventional typeincluding, for example, period are thereby provided with a more uniform .an endless chain carrying cups or buckets 2| Atreatment. t i 55' whereby the used particles are returned to the vnetic material.

bin I to the abrasive projecting apparatus I2 and collecting and returning the projected particles to the main bin by the conveyor means I8 and I9.

The impingement of the abrasive particle onA the articles I 6 will cause some of the particles to be broken, and further recirculation of the broken abrasive particles will result in further breaking of such partly broken particles so that eventually some of the abrasive will be lost fro-m the system in the form of dust. In addition to the disintegration of the abrasive, other particles will escape from the system so that the. supply will be steadily depleted.. The invention includes means for automatically adding abrasive particles to the main supply circuit when the particles .stored in the. main `bin on hopper: III are depleted below a predetermined quantity. or below a predetermined level, whereby thel abrasive in the. main bin is replenishedbefore the bin I0 is completely exhausted.

In carrying out the invention',kthe abrasive is preferably addedto the main abrasive circuit, such as to the conveyor means I8.. The means for admitting abrasive particles tof the conveyor I8. from a replenishing bin 60 is only operable when the abrasive inthe main bin I0 falls below abrasive particles may therefore bey storedin the replenishing bln 60 so as to be. normally guided into thev conveyor I8 by means of a conduit 6I 'f in open communication with the conveyor I8. 'I'he conduit 6I is preferably formed of non-mag- The downward movement of abrasive particles. from the replenishing bin 60 may be interruptedv or blocked by any suitable' means, such as an inductive coil 62, which may, for example, surround the conduit 6I, and-when this coil'is energized magnetizable abrasive particles such as steelshotwill be blocked by the flux set upby the magnetic iield provided by the coil 62.

'I'he embodiment of the invention shown in the drawing includes means for rendering such blocking meansloperative. Thus,v an electrical source indicated at |53l may be provided, coupled with a circuit 64 and vmeans for closing the. supply source acrossthe coil 62, when the abrasive stored in the main bin III is. above a predetermined cuantity. Thecircuit 64 may be closed .by any suitable means suchl asv a stationary contact member 66 which maybe engaged by. a movable contact member 61'. These contactsare preferably arranged to be normally open, andthe contact member 61 is pivotally mounted at 68.

The contacts may be moved to a closed position by any suitable means such as a permanent'mag` net 69 which is drawn to the right when the particles stored in the main hopper In are above a predetermined level. For this purpose the abrasive particles are of a magnetizable character feed spout Il into the abrasive projecting apparatus I2, and the projected particles are returned to the main bin I 0 for recirculation through the projecting apparatus by means of the conveyor I8 and the elevator I9. As long as the abrasive in the main bin l0 is above a. predetermined level the magnet 69 will'remain attracted to the magnetizable particles in the main bin and to the right in the drawing, so that the contacts 66 and 61 will be closed to supply current to the coil 62. The flux set up by the inductivey coil 62 will magnetize the particles in the non-magnetic conduit 6I and block downy y ward movement of the abrasive particles through the conduit means 6I. When the abrasive in the main bin IIl falls below a predetermined level the magnet 69, will no longer be attracted to any magnetizable material and the contact member 61 will swing to the left and the coil 62 will be de-energized. Thereafter the abrasive from the replenishing `bin may flow into the conveyor means I8 through the conduit 6I and be elevated into the main bin III.

While the invention has been described with reference to specific structural details such as the pipes and conduits, it will be appreciated that changes may be made therein by those skilled in the art. Such modifications and alterations in the electrical features described may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim:

1. In abrasive blasting apparatus, a main bin for storing abrasive particles, abrasive projectingapparatus, means providing a circuit for guidingabrasive particles from said bin to the abrasive projecting apparatus and returning the projecting particles to said bin, an auxiliary source of abrasive particles, means for guding'particles from said auxiliary sourcedownwardly into said circuit, means for interrupting, the downward movement of particles in said guide means, a source of current, a circuit for connecting said source to said means, and means actuated when a predetermined quantity of abrasive is presentv Vreplenishing bin for depositingparticles therefrom into said circuit, an electro-magnetic valve for interrupting the movement'of particles in said conduit, an electrical source, an electrical circuit including therein said sourcel and said e1ectromagneticvalve,l and means for'closing said'electrical circuit to said electroemagnetic valve when the quantity of abrasive stored inthe main. bin is above a predetermined amount.

3. In abrasive blasting apparatus, a main bin :for storing magnetizable abrasive'particles, abra sive projecting y`apparatus receivingiparticles from said' bin, means collecting the projected particles, conveyor means returningthe collected particles into said main bin, a replenishing bin for storing a supply of magnetizable abrasive particles, a non-magnetic conduit for guidingf particles from the replenishing bin into said conveyor means, an inductive coil adjacent said conduit,

a magnet movably mounted adjacent an upper abrasive particles from said bin to the abrasive projecting apparatus and returning the projected particles into said bin, means for feeding abrasive particles from an auxiliary source into said circuit, means for interrupting the movement of abrasive particles from the auxiliary source into said circuit, and means operable upon the presence of `a predetermined quantity/ of abrasive in said bin for rendering said interrupting means 10 operative.

CHARLES M. GOSSARD. 

